This invention relates to a novel method for the production of porous spheres of calcium phosphate compound. More particularly, this invention relates to a method for the production of porous spheres of calcium phosphate compound possessing a large specific surface area and uniform sphere diameter and pore diameter and useful as a material for filling cavities in human teeth or bones and as a stationary phase material for liquid chromatography.
It has been known that calcium phosphate compounds show specific affinity for vital tissues and vital components and, therefore, are usable as a material for filling cavities in bones. For example, it has been known that apatite hydride is the main component of such rigid vital tissues as bones and teeth and that when it is used as a filling material for repairing bones, it exhibits an ability to induce growth of bone tissues on the surface of its own mass. Tricalcium phosphate is also usable as a material for repairing bones. It has been known that these compounds are integrally combined with bone and then dissolved and absorbed so as to substitute for bone.
Further, it has been known that these calcium phosphate compounds exhibit specific affinity for such vitally related substances as amino acids, proteins, and hormones and, therefore, are usable as stationary phase materials for chromatographic separation and concentration of these substances.
For the calcium phosphate compounds to be effectively used for the purpose just mentioned, they are required to be in the form of porous spheres having a large specific surface area and substantially uniform sphere diameter and pore diameter.
Heretofore, as means for producing porous particles of calcium phosphate, a method which comprises first preparing calcium phosphate powder by dry and wet method and then converting this powder into porous particles through the steps of molding, sintering, pulverization, and classification, for example, has been widely used.
With this method, however, the process of production is complicated and the shape of the porous particles formed, the particle diameter and the pore diameter thereof are difficult to control. Use of this method to obtain porous particles with the desired properties, therefore, inevitably entails inferior productivity and high cost of production.
This invention has been attained for the purpose of overcoming the drawbacks suffered by the conventional methods for production of porous particles of calcium phosphate compound described above and providing a method capable of producing, through a simple procedure, porous spheres of calcium phosphate compound having a large specific surface area and substantially uniform sphere diameter and pore diameter without entailing any difficulty in the control of the shape of the spheres, the sphere diameter, and the pore diameter.